Screw-cutting machine



(No Model.) 2 Sheets-Sheet 1.

J. H. STERNBERGH. SCREW CUTTING MACHINE.

Patented Apr. 16, 1889.

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(No Model.) 4 2 Sheets-Sheet 2.

J. H. STERNBERGH.

SGREW CUTTING MACHINE.

Patented Apr. 16, 1880.

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JAMES WIERNBERGII, OF READING, PENNSYLVANIA.

SCREW-CUTTING MACHINE.

STPEOIFICATION forming part of Letters Patent No. 401,600, dated April 16, 1889.

Application filed Jan ar 26, 1889. Serial No. 297,646. (No-model.)

To all whom it may concern]- Be it known that 1, JAMES H. STERNBERGH, a citizen of the United States, residin gat Reading, in the county of Berks and State of Pennsylvania, have invented certain new and use ful Improvements in Screw-Cutting Machines; and I do declare the following to be a full, clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

In screw-cutting machinery separate out ting-tools of different forms have heretofore been secured to the front of the die-head and adapted to be moved toward or away from the center either radially or by an oscillating movement.

My invention is adapted more particularly to that form of cutter which is provided with a longitudinally-groovcd face adapted to be held at a tangent to the blank. This cutt(r is very easily sharpened by grinding, thus offecting a great saving in the maintenance of good cutters, and my main object is to provide a simple mechanism for holding and operating them, which will insure satisfactory results by positively and firmly maintaining the cutters in any desired and easily-regulated position, and thus forming clean-cut threads of standard size. Tothis end I avoid the use of screws and gearing with their necessary lost motion.

The features of my invention include in the first place parallel axial bars passing through the die-head and engaging holders inovably secured to the front of the same, as many bars being used as there are holders. The front end of each bar is preferably made to engage opposite sides of two adjacent holders in such the diameter. of the thread to be cut, and in details of the preferred construction shown in the accompanying drawings and description and set forth in the claims.

Figure 1 is a full front view of the diehead with the retaining-ring removed. The two lower cutters are represented as open while the two upper are closed to a working position. Only two of the axial bars are in position. Fig. 2is a longitudinal section through XY of Fig. 1, showing, also, the retaining-ring and guard in section through V IV of Fig. 5. Fig. 3 is a perspective view of the cutterholder with a longitudinally-grooved cutter in position. Fig. 4 is a perspective view of one of the axial bars. Fig. 5 is a view of the retaining-ring and removable guard, a section of which is shown in Fig. 2. Figs. 6,7, 8, and 9 show modified arrangements of the axial bars and cutter-holders. Figs. 10 and 11 show a modified holder provided with a grooved wheel adapted to form a thread by rolling.

The die-head A is secured to the end of the mandrel B, which maybe hollow or partly hollow, as shown, to permit the threading of any length of bolt. The enlarged front of the head has cutter-holders of the form shown in Fig. 3 pivoted thereto, trunnions C on the holders fitting into holes A in the head, which latter may be recessed at A to let the holders in flush with the projecting portion of the head, to which the retaining-ring hereinafter described is secured.

The cutters C are fiat bars of steel having one side, 0*, grooved longitudinally to suit the form and size of thread which it is desired to out. They fit snugly in slots 0 formed in the rectangular holders 0, and are clamped therein by means of face-screws at C after having been properly adjusted by the set-screws G which project from the outer ends of the holders. The base of the slot 0 is not parallel wit-h the base of the holder, but is inclined, so as to make the position of the cutter correspond with the angle of the thread, as indicated more clearly in Fig. 2. The trunnions C, before referred to, project one from the slotted face of the holder and another from the opposite face, near the outer end. Reversed inclines or wedge-shaped projections O and G are formed opposite each other on the remaining two faces of the holder near the inner or cutter end, but at difierent distances from the trunnion.

Bars E, formed with square heads or ends E having reversedwedge-shaped adjoining sides E and E, are passed axially through parallel openings A in the head and are secured to a sleeve, D,sliding on the mandrel B in the rear of the head. These openings A are so arranged as to bring the wedges E and E on the ends of the axial bars E in contact, respectively, with the corresponding inclines O of one holder and O of another adacent holder. For convenience in referring to the different holders they are marked, re spectively, 1,2, 3, and at in Fig. 1, in which it will be noticed that the head E of one bar engages the holder marked 1 on its incline C nearest the pivotal point C, and also the adjacent holder (marked 4) on its incline C farther from the pivotal point, and the holders marked 2 and 3 are similarly engaged by the inclines on the head of the other bar shown. The two bars which are omitted in the figure are arranged in the same way, so that each holder is held between oppositelyinclined wedges. As these wedges are all moved backward simultaneously by means of the sliding sleeve D, to which their rear ends are connected, the head of each bar forces one of the holders away from the center of the head, and at the same time releases the adjacent holder as rapidly, and onlyas rapidly, as another bar forces the latter holder away from the center, so that each holder is turned on its trunnions C to a position similar to holders marked 2 and 3, yet is constantly and firmly held between the oppositely-inclined wedges at every point of its movement. A forward movement of the sleeve D will in a similar manner force the cutters simultaneously toward the center.

The nut J upon the rear of the head serves as an adjustable stop for the sleeve D, by means of which the diameter of the thread to be out can be regulated to the greatest nicety. As soon as the cutters get to work, their inclination to dig in to the blank presses the inclined sides of the holders against the wedge-shaped ends of the axial bars E, tending to move the latter, which are positively stopped, however, when the sleeve D is pulled tight against the nut J, so that threads of uni form size are assured.

The retaining-ring F (shown in Figs. 2 and 6) is fastened to the head by means of screwbolts K, passing through holes F, while the outer trunnions, O, on the holders are supported in holes F in the ring, the holders being free to swing upon them, but without lost motion.

In order to protect the operator, and at the same time to serve as a guide for the blank in entering the die, a guard, G, consisting of a central ring with opening G and arms reaching to the periphery of the ring F, is removably secured to the latter by screws H,

thus permitting its ready removal, when desired, without interfering with the ring itself.

It is evident that in the construction described the incline E of the bar E and O of the holder should be somewhat less than the inclines E and C owing to their being nearer the center of rotation, U. I do not, however, limit myself to the construction set forth, as it may be readily modified without departing from the spirit of my invention, which consists, essentially, in the use of movable cutterholders and an equal number of parallel adj usting-bars passed axially through the head.

Fig. 6 illustrates a modified form in which a single incline is employed on both the holder and the end of the axial bar E, springs L being employed to press the holders outward, instead of the inclines E of the bar and C of the holder, already described.

Fig. 7 indicates another modification, in which an ordinary cutter, M, having the desired thread cut on the end, has a radial movement in the front of the head, instead of an oscillating movement,as before described, motion being communicated to it from the axial bar E by means of a projection, E on the end of the latter engaging an oblique slot, C in the side of the holder.

Figs. 8 and 9 are an irregular section and a front view of another modified arrangement, in which the axial bars E are arranged to oscillate the pivoted holders 0 by means of a rotary movement instead of an axial movement, as previously described, cams E and E on the front end of the bars engaging adjacent holders (as those marked 1 and 4 in Fig. 9) on opposite sides and at different distances from the center of rotation,-C'. The cam E is somewhat smaller than E for the same reason that the incline E is less than E in the construction first described, the principle of operation and the function of the two devices being similar. These rotary bars may also be operated by means of a sliding sleeve, D, as shown in Fig. 8, spiral grooves E near the rear end of the bars being engaged by pins D which give the bars a rotary motion as the feathered sleeve is moved axially. It is obvious that other modifications may be devised, and I do not limit my invention to those shown.

Instead of using cutting-tools in the holders, the thread may be formed by means of a wheel, N, mounted in the end of the holder, as shown in Figs. 10 and 11. The surface of this wheel is provided with parallel grooves corresponding in form and spacing with the thread to be cut and angled to the proper pitch, and the thread is rolled on the heated blank by pushing the latter into the center of the revolving head A, the rollers N being carried with the head and their distance from the center regulated in the same manner as the cutters. This revolution of the head A and the contact of the rollers N, preferably three or four in number, with. the blank gives the rollers a secondary movement around vwith the movably-secured cutter-holders, of

separate bars passing through the head and having ends engaging said holders, and means for simultaneously operating said bars, all substantially as set forth.

2. In a die stock or head, the combination, with the pivoted cutter-holders, of separate bars passing through the head, the front end of each bar engaging opposite sides of two adjacent holders, and means for simultaneously operating said bars, all substantially as set forth.

3. In a die stock or head, the combination, with the movably-secured cutter-holders, of separate bars connected to a sliding sleeve and passing through the head, the free ends of said bars engaging said holders, and all adapted to operate substantially as set forth.

4. In a die stock or head, pivoted cutterholders, each having a beveled side, in combination with axial bars passing through said die-head, and each having a beveled surface engaging the beveled side of a holder, and means for simultaneously operating said bars, substantially as and for the purpose set forth.

5. In a die stock or head, pivoted cutterholders having oppositely-beveled sides, substantially as described, in combination with axial bars passing through said die-head and having correspondingly-beveled surfaces,

each, of which engages a beveled side of a holder, and means for simultaneously operatin g said bars, substantially as and for the purpose set forth.

6. In a die stock or head, the cutter-holders with inclined slots 0 pivoted to said head by trunnions, and the rectangular longitudinally-grooved cutters adjustably secured in said slots, substantially as described, in combination with means for oscillating said holders, substantially as and for the purpose set forth.

'7. In a die stock or head,the cutter-holders with trunnions (3', pivoted to the head and provided with cutters and adjusting-screws, in combination with a retaining-ring secured to the head and having bearings for said trunnions, all substantially asset forth.

8. In a die stock or head, the combination, with cutter-holders secured thereto and a retaining-ring, of a guard, G, with central opening,re1novably secured to said ring, substantially as and for the purpose set forth.

9. In a die stock or head, the combination, with the adjustable cutter-holders secured thereto, and a sliding sleeve and connected mechanism for operating said holders, of a stop for said sleeve, adjustably secured to the head, substantially as and for the purpose set forth.

10. In a die stock or head, the combination, with the adjustable cutter-hol ilers secured thereto, and a sliding sleeve and mechanism, substantially as described, for operating said holders, of a nut, J, adapted to serve as a stop for said sleeve, substantially as and for the purpose set forth.

In testimony whereof I affix my signature in presence of two witnesses.

JAMES H. STERNBERGH.

WVit-nesses:

H. M. M. RICHARDS, HARRY O. GABLE. 

